From 318fe782539c4150d1b8e4e6c9dc3a896512cb8a Mon Sep 17 00:00:00 2001 From: Suravee Suthikulpanit Date: Thu, 24 Jan 2013 13:17:53 -0600 Subject: [PATCH] IOMMU, AMD Family15h Model10-1Fh erratum 746 Workaround The IOMMU may stop processing page translations due to a perceived lack of credits for writing upstream peripheral page service request (PPR) or event logs. If the L2B miscellaneous clock gating feature is enabled the IOMMU does not properly register credits after the log request has completed, leading to a potential system hang. BIOSes are supposed to disable L2B micellaneous clock gating by setting L2_L2B_CK_GATE_CONTROL[CKGateL2BMiscDisable](D0F2xF4_x90[2]) = 1b. This patch corrects that for those which do not enable this workaround. Signed-off-by: Suravee Suthikulpanit Acked-by: Borislav Petkov Cc: stable@vger.kernel.org Signed-off-by: Joerg Roedel --- drivers/iommu/amd_iommu_init.c | 34 ++++++++++++++++++++++++++++++++++ 1 file changed, 34 insertions(+) diff --git a/drivers/iommu/amd_iommu_init.c b/drivers/iommu/amd_iommu_init.c index 81837b0710a9..faf10ba1ed9a 100644 --- a/drivers/iommu/amd_iommu_init.c +++ b/drivers/iommu/amd_iommu_init.c @@ -974,6 +974,38 @@ static void __init free_iommu_all(void) } } +/* + * Family15h Model 10h-1fh erratum 746 (IOMMU Logging May Stall Translations) + * Workaround: + * BIOS should disable L2B micellaneous clock gating by setting + * L2_L2B_CK_GATE_CONTROL[CKGateL2BMiscDisable](D0F2xF4_x90[2]) = 1b + */ +static void __init amd_iommu_erratum_746_workaround(struct amd_iommu *iommu) +{ + u32 value; + + if ((boot_cpu_data.x86 != 0x15) || + (boot_cpu_data.x86_model < 0x10) || + (boot_cpu_data.x86_model > 0x1f)) + return; + + pci_write_config_dword(iommu->dev, 0xf0, 0x90); + pci_read_config_dword(iommu->dev, 0xf4, &value); + + if (value & BIT(2)) + return; + + /* Select NB indirect register 0x90 and enable writing */ + pci_write_config_dword(iommu->dev, 0xf0, 0x90 | (1 << 8)); + + pci_write_config_dword(iommu->dev, 0xf4, value | 0x4); + pr_info("AMD-Vi: Applying erratum 746 workaround for IOMMU at %s\n", + dev_name(&iommu->dev->dev)); + + /* Clear the enable writing bit */ + pci_write_config_dword(iommu->dev, 0xf0, 0x90); +} + /* * This function clues the initialization function for one IOMMU * together and also allocates the command buffer and programs the @@ -1172,6 +1204,8 @@ static int iommu_init_pci(struct amd_iommu *iommu) iommu->stored_l2[i] = iommu_read_l2(iommu, i); } + amd_iommu_erratum_746_workaround(iommu); + return pci_enable_device(iommu->dev); } -- 2.30.2